1164 



SURGICAL AND TOPOGRAPHICAL ANATOMY 



magnum, which supports the third or longest digit, and is the bone of the carpus 

 most exposed to injury. A line drawn from the base of the fifth metacarpal bone 

 to the radio-carpal joint, slightly curved downwards, will give the line of the 

 carpo-metacarpal joints (Windle). 



When the lingers are flexed, it will be seen that in each case it is the proximal 

 bone which forms the prominence; thus, the knuckle is formed by the head of the 

 metacarpal the interphalangeal prominence by the head of the first phalanx, and 



Fig. 728.— Axastomoses and DiSTRiBrriox of the Aktkiues of the Hand. 



7 



Anterior interosseous 



Radial artery 



Anterior radial carpal 



Svperficial volar 

 Posterior radial carpal 

 Radial artery at wrisi 



Dorsalis polticis 



Metacarpal or 



first dorsal 



interosseous 



Princeps pollicis 



Dorsalis indicts 

 Radialis indici. 



First dorsal branch of collateral 

 digital 



Second dorsal branch o/ collateral 

 digital 



Anastomosis of collateral digital 

 arteries about matrix of nail 

 and pulp of finger 



Ulnar artery 



Anterior ulnar 

 carpal 



Posterior ulnar 

 carpal 



Deep ulnar 

 Superficial arch 



Carpal recurrent 



Posterior communi- 

 cating or perforat- 

 ing 



Palmar interosseous 



Second, third, and 

 fourth palmar 

 digital 



S-rond and third 

 dorsal interosseous 



First palmar digital 



A uterior communi- 

 cating or perforat- 

 ing 



the distal one by the head of the second. Thus, the joint in each case lies below 

 the iirominence, the distal joint being one-twelfth of an incli (2 mm.), the inter- 

 phalangeal one-sixth (4 mm.), and the metacarpo-phalangeal one-third (8 mm.) 

 below its i)r()ininence. 



Skin folds.— Two or three of these are seen on the palmar surface of the wrist; 

 two lower down, and usually close together; and one less well marked a little 

 higher up upon the forearm. None of these correspond exactlv to the wrist-joint 

 (page 1159). The lowest ' precisely crosses the arch of the os niasnum in the line 

 of the third metacarpal l^one' (Tillaux), and is not quite three-quarters of an inch 



